Growing ordered CuO nanorods on 2D Cu/g-C₃N₄ nanosheets as stable freestanding anode for outstanding lithium storage

Two dimensional (2D) nanostructures are promising to provide a new hierarchical architecture for transition metal oxides (TMOs) with outstanding lithium storage. In this work, we grew ordered CuO nanorods on 2D Cu/g-C₃N₄ nanosheets to form the hierarchical CuO@Cu/g-C₃N₄ nanorods film as freestanding anode for advanced lithium storage. This assembled freestanding film demonstrates a high discharge specific capacity at 726 mAhg⁻¹ after 200 cycles at 0.1C and a discharge specific capacity of 457 mAhg⁻¹ after 625 cycles at 1C, among the best performance in CuO and CuO based nanostructures for lithium storage. Its outstanding stability and cyclic performance are ascribed to the following aspects during the reaction process: (i) the unique 2D nanostructure provides large exposed area for Li⁺ insertion, (ii) the ordered CuO nanorods provide interior spaces to accommodate the volume change and offer more paths for charges and Li⁺ transfer, (iii) the existence of Cu nanosheets increases the electrons transport and (iv) the porous g-C₃N₄ nanosheets endow the prepared structure more active sites for facilitating Li⁺ transport and accommodating volume change. Our strategy on growing ordered nanostructures on 2D nanosheets will be an effective way to modify TMOs for advanced lithium-ion batteries.